Threaded Connection with Secure Shoulder Ring for Electrical Submersible Pump

ABSTRACT

An electrical submersible pump assembly has modules including a pump, a motor, and a seal section. A drive shaft assembly extends from the motor through each of the modules. A threaded connection between at least two of the modules includes a first adapter having external threads and a second adapter having a neck with an external load shoulder. A collar is rotatably carried and axially movable on the neck. The collar has internal threads and an internal load shoulder. A shoulder ring having two segments encircles the neck. The shoulder ring has a first surface in abutment with the external load shoulder and a second surface in abutment with the internal load shoulder. A resilient ring tits around an outer diameter of the shoulder ring for retaining the ring segments on the neck prior to the collar being in threaded engagement with the threads of the first adapter.

FIELD OF THE DISCLOSURE

This disclosure relates in general to electrical submersible pumps for wells and in particular to a threaded connection between modules of a pump assembly having a shoulder ring that is secure against accidental dropping.

BACKGROUND

Electrical submersible pumps (ESP) are commonly used in wells for hydrocarbon fluid production. An ESP is made up of a number of modules brought to the well site. These modules include a pump, a motor, and a seal section, or pressure equalizer. The modules may also include a gas separator. Additionally, the pump and motor may comprise tandem modules that are connected at the well site. The connections may be bolted flanges, or they may comprise threaded collars.

A typical threaded collar connection has an adapter on one module with a neck that carries a rotatable collar. The collar can be moved axially to engage threads on an adapter on the module to be joined. A shoulder ring fits in a groove on die neck to transfer the axial load from the collar through the shoulder ring and to the adapters. The shoulder ring usually comprises two halves that are placed in the groove. Often, the modules are made up while the ESP is assembled above the rig floor. A chance exists that the shoulder ring halves could fall out of the groove before the collar is moved up around them. If the well is uncovered at this point, the shoulder ring halves could drop into the well, causing serious problems.

SUMMARY

As electrical submersible pump assembly has a plurality of modules including a pump and a motor. A drive shaft assembly has an axis and extends from the motor through each of the modules. A threaded connection between at least two of the modules comprises a first adapter having threads and a second adapter having a neck with an external load shoulder. A collar is rotatably carried and axially movable on the neck, the collar being in threaded engagement with the threads of the first adapter. The collar has an internal load shoulder axially spaced from and facing in a direction opposite to the external load shoulder. A shoulder ring encircles the neck and comprises a plurality of separate ring segments. The shoulder ring has a first surface in abutment with the external load shoulder and a second surface in abutment with the internal load shoulder to transfer an axial load between the first and second adapters. A retaining means retains the ring segments on the neck prior to the collar being in threaded engagement with the threads of the first adapter. The retaining means remains a part of the assembly after the collar is secured to the first adapter.

In one embodiment, the retaining means comprises a resilient ring that fits around an outer diameter defined by the ring segments. In this embodiment, a circumferentially extending groove segment on an outer side of each of the ring segments defines an annular retaining ring groove when the ring segments are installed around the neck. The resilient ring locates in the retaining ring groove. The resilient ring may be elastomeric. The resilient ring has an outer diameter side spaced radially inward from any portion of the collar.

In another embodiment, a roll pin protrudes from at least one of the ends of one of the ring segments. The roll pin is received within a hole in at least one of the ends of the other of the ring segments.

In still another embodiment, a hinge connects the first end of one of the ring segments to the first end of another of the ring segments. A roll pin protrudes from one of the second ends and is received within a hole in the other of the second ends.

In still another embodiment, the retaining means comprises a pawl protruding from at least one of ends of one of the ring segments into engagement with a lip on at least one of the ends of another of the ring segments.

In still another embodiment, a detent is located on an inner diameter portion of each of the ring segments adjacent one of the ends of the ring segments. A mating detent recess on the neck receives the detents.

Preferably, the ends of one of the ring segments are closely spaced to the ends of another of the ring segments when the ring segments are installed around the neck.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cropped side view of an electrical submersible pump assembly in accordance with this disclosure.

FIG. 2 is a cross-sectional view of one of the threaded connections of the pump assembly of FIG. 1.

FIG. 3 is a perspective view of a first embodiment of a shoulder ring for the threaded connection of FIG. 2, with the two halves of the shoulder ring shown spaced from each other.

FIG. 4 is a top view of a second embodiment of a shoulder ring for the threaded connection of FIG. 2.

FIG. 5 is a perspective view of a third embodiment of a shoulder ring for the threaded connection of FIG. 2.

FIG. 6 is sectional view of a fourth embodiment of a shoulder ring for the threaded connection of FIG. 2, and shown secured to the adapter that carries the threaded collar.

FIG. 7 is a sectional view of a fifth embodiment of a shoulder ring mounted for the threaded connection of FIG. 2.

FIG. 8 is a top view of a sixth embodiment of one-half of a shoulder ring for the threaded connection of FIG. 2.

FIG. 9 is a side view of the shoulder ring half of FIG. 8.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to FIG. 1, electrical submersible pump (ESP) 11 is employed to pump well fluid, typically a mixture of oil and water. ESP 11 may be installed in a vertical portion or a horizontal or inclined portion of a well. The terms “upper”, “lower” and the like are used only for convenience and not in a limiting manner.

ESP 11 has a number of modules, including a pump 13 that may be a centrifugal pump having a large number of stages, each stage having an impeller and a diffuser (not shown). Alternately, pump 13 may be another type, such as a progressing cavity pump. Pump 13 has an intake 15 for drawing in well fluid. A pressure equalizer or seal section 17 connects to the lower end of intake 15 in this example. An electrical motor 19 connects to the lower end of seal section 17. Seal section 17 may be conventional and has components for reducing a pressure difference between lubricant in motor 19 and the hydrostatic pressure of the well fluid. ESP 11 could have other modules, such as a gas separator or additional pumps, seal sections and motors in tandem (not shown).

The various modules, including pump 13, seal section 17, and motor 19 are typically brought separately to a well site and connected together by connections 21 and 23. In this examples each connection 21, 23 comprises a threaded connection. However, some of the connections between modules could be bolted types. FIG. 2 illustrates the threaded connection 21 between seal section 17 and pump intake 15; the other threaded connection 23, which is between motor 19 and seal section 17, may be constructed in the same manner.

Referring to FIG. 2, an adapter or head 25 has external threads 27 that secure to internal threads in the upper end of a housing (not shown) for seal section 17. Adapter 25 has an upward protruding neck 29 of smaller diameter than fee housing of seal section 17. Neck 29 has an annular external groove 31 that may have a rectangular cross-section.

A collar 33 surrounds neck 29. Collar 33 comprises a sleeve with internal threads 35 at its upper end. Collar 33 is axially movable along axis 37 and rotatable relative to neck 29. Collar 33 has an outer diameter that may be the same as the outer diameter of seal section 17 (FIG. 1). Collar 33 has a lower released position, with its lower end abutting an upward facing shoulder 38 on adapter 25. Collar 33 has an upper engaged position, shown in FIG. 2, with its lower end spaced above shoulder 38. Collar 33 has a cylindrical inner diameter portion or recess 39 with an annular internal upward facing load shoulder 41 that aligns with the lower edge of groove 31 when collar 33 is in the upper engaged position.

A shoulder ring 43 closely fits within external groove 31. In this example, shoulder ring 43 is rectangular in cross section, has an upper edge abutting an upper edge or external downward facing shoulder of groove 31. Shoulder ring 43 has a lower edge resting on a lower edge of groove 31 when collar 33 is secured to another module. Shoulder ring 43 has a greater radial thickness than the radial depth of groove 31, thus protrudes radially outward from groove 31. The inner diameter of shoulder ring 43 may abut the outward facing cylindrical surface of external groove 31. An outer portion of shoulder ring 43 rests on collar upward facing shoulder 41.

Seal section adapter 25 secures to a pump intake adapter 45 in this example. Intake adapter 45 is a tubular member with upper external threads 47 that secure to internal threads in a housing (not shown) of pump 13. Intake adapter 45 has a downward facing shoulder 49 that abuts an upward facing shoulder 51 of seal section adapter 25. Shoulders 49, 51 may have anti-rotation features, such as knurling, to prevent rotation of intake adapter 45 relative to seal section adapter 25. Intake adapter 45 has external threads 53 that are engaged by internal threads 35 of collar 33. Tightening collar 33 to threads 53 causes internal load shoulder 41 to bear against the lower edge of shoulder ring 43 to transmit an axial load through the upper edge of groove 31 into adapters 25 and 45.

Referring to FIG. 3, in this embodiment, shoulder ring 43 is formed in two separate halves 43 a, 43 b. Each ring half 43 a, 43 b extends 180 degrees and has two ends 55. Ring halves 43 a, 43 b have retaining means to retain them on external groove 31 before collar 33 is made up with adapter 45 (FIG. 2). In FIG. 3, the retaining means includes a roll pin 57 secured to and protruding from each end 55 of ring half 43 a. A mating hole 59 is drilled in each end 55 of ring half 43 b. While inserting ring halves 43 a, 43 b into external groove 31 (FIG. 2), roll pins 57 will be pressed into holes 59. Each roll pin 57 is a conventional roll pin that has an initial outer diameter slightly larger than holes 59, but radially deforms when inserted to form a tight fit. Alternately, each ring half 43 a, 43 b could have only one roll pin 57 and one hole 59. Also, a single roll pin 57 and a single hole 59 for shoulder ring 43 is feasible.

Often the modules of ESP 11 (FIG. 1) are made up while suspended by a workover rig above a well. The engagement of roll pins 57 with holes 59 prevents ring halves 43 a, 43 b from accidentally falling out of external groove 31 (FIG. 2) and into the well during make up of ESP 11.

Referring to FIG. 4, in this embodiment, shoulder ring 61 has two ring halves 61 a, 61 b connected at one of their ends by a hinge 63. A roil pin 65 protrudes from the other end of ring half 61 b. A mating hole 67 is formed in the other end of ring half 61 a. Roll pin 65 is pushed into hole 67 while shoulder ring 61 is being installed in external groove 31 (FIG. 2). Roll pin 65 operates in the same manner as roll pins 57 of FIG. 3.

Referring to FIG. 5, in this embodiment shoulder ring 69 is formed in two halves 69 a, 69 b. A pawl 71 extends from each end of ring half 69 a. Pawl 71 is slightly resilient and has a lip 73 on its outer end. Lip 73 snaps into and engages a transversely extending groove 75 formed in each end of ring half 69 b. Alternately, each ring half 69 a, 69 b could have one pawl 71 and one mating groove 75. Also, rather than two pawls 71, a hinge (not shown) similar to hinge 63 (FIG. 4) could connect one of the ends of ring halves 69 a, 69 b.

In the embodiment of FIG. 6, shoulder ring 77 has two ring halves 77 a, 77 b. Each ring half 77 a, 77 b has a rib or detent 79 on its internal diameter. Detents 79 are located at mating ends 80 of ring halves 77 a, 77 b. An axially extending recess or groove 81 is formed in external annular groove 82 of seal section adapter 83 for receiving detents 79 as the ring halves 77 a, 77 b are pressed into external groove 82. The inner diameters of ring halves 77 a, 77 b are formed such that detents 79 snap into axially extending recess 81.

FIG. 7 shows another embodiment. Seal section adapter 85 has an external groove 87 that receives a shoulder ring 89 formed into a plurality of segments that may be two halves. Similar to the other embodiments, external groove 87 has a downward facing external shoulder 87 a. An upper or first surface of shoulder ring 89 bears against internal shoulder 87 a.

Shoulder ring 89 is similar to the shoulder ring halves of FIGS. 3, 5 and 6 except there are no rolls pins 57, pawls 71 or detents 79. The retaining means for retaining shoulder ring 89 in groove 87 includes a retaining ring groove segment 91, which may be semi-circular in cross section, formed on the outer diameter of each of the two halves of shoulder ring 89. When the segments of shoulder ring 89 are placed around the neck of adapter 85, the retaining ring groove segments 91 align to define an annular retaining ring groove. A circular retainer ring 93 fits tightly within retaining groove 91 to keep the two halves of shoulder ring 89 from falling out of seal section adapter groove 87. Retainer dug 93 may be a resilient elastomeric ring, as shown, and once installed, it is under tension.

Collar 95 has an inner diameter portion or recess 97 with an upward facing internal load shoulder 99 that faces external load shoulder 87 a. Internal load shoulder 99 engages a lower or downward facing surface of shoulder ring 89. The outer diameter of retainer ring 93 preferably does not touch or seal against any portion of recess 97; rather it is spaced radially inward from collar 95.

Pump intake adapter 101 has external threads 103 that are engaged by internal threads 105 of collar 95. A rotatable drive shaft 107 within seal section adapter 85 has an upper end that conventionally couples in a lower end of a drive shall 109 in pump intake adapter 101. A coupling sleeve 110 with internal splines connects shafts 107, 109 for rotation therewith.

After the segments of shoulder ring 89 are placed in groove 87, retainer ring 93 is stretched, moved down over the segments and fitted into retaining ring groove 91. Then collar 95 is moved up around retainer ring 93 and related to secure threads 103, 105. Tightening collar 95 causes an axial load to pass from internal load shoulder 99 through shoulder ring 89 and external load shoulder 87 a into adapters 85 and 101.

Referring to FIG. 8, in this embodiment, ring half 111 has a mating half (not shown) that is identical. Each ring half 111 is semi-cylindrical, having two ends 113. The extent of each ring half 111 is slightly less than 180 degrees, resulting in a gap 115 between the ends 113 of one ring half 111 and the other when they are installed within groove 31 (FIG. 2). Ends 113 do not abut each other in this embodiment.

Also, as shown in FIG. 9, each ring half 111 is formed with a slight arc or bow in an axial direction relative to axis 117, resulting in a convex or outward bowed side 119 and a concave side 121. Ring half 111 has an axial thickness 123 measured from convex side to concave side 121 at any point that is constant and slightly less than the axial dimension of groove 31 (FIG. 2). Prior to installation in groove 31, the bowing causes an overall axial dimension 125 from the axial center of convex side 119 to the junction of either end 113 with concave side 121 to be greater than axial thickness 123. Also, the overall axial dimension 125 is slightly greater than the axial dimension of groove 31. When ring half 111 is inserted into groove 31, it elastically deforms, with the overall distance 123 decreasing to the axial dimension of groove 31. The elastic deformation wedges convex surface 119 against an upper edge of groove 31 and concave surface 121 against the lower edge of groove 31. The friction created by this elastic deformation wedges ring halves 111 in groove 31, preventing them from accidentally falling out.

Although the disclosure has been shown in several of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the disclosure. 

1. An electrical submersible pump assembly, comprising: a plurality of modules including a pump and a motor; a drive shaft assembly having an axis and extending from the motor through each of the modules; a threaded connection between at least two of the modules, comprising: a first adapter having threads; a second adapter having a neck with an external load shoulder; a collar rotatably carried and axially movable on the neck, the collar being in threaded engagement with the threads of the first adapter, the collar having an internal load shoulder axially spaced from and facing in a direction opposite to the external load shoulder; a shoulder ring encircling the neck and comprising a plurality of separate ring segments, the shoulder ring having a first surface in abutment with the external load shoulder and a second surface in abutment with the internal load shoulder to transfer an axial load between the first and second adapters; and retaining means for retaining the ring segments on the neck prior to the collar being in threaded engagement with the threads of the first adapter, the retaining means remaining a part of the assembly after the collar is secured to the first adapter.
 2. The assembly according to claim 1, wherein the retaining means comprises a resilient ring that fits around an outer diameter defined by the ring segments.
 3. The assembly according to claim 1, wherein the retaining means comprises: a circumferentially extending groove segment on an outer side of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; and a resilient ring that locates in the retaining ring groove.
 4. The assembly according to claim 1, wherein the retaining means comprises: a circumferentially extending groove segment on an outer side of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; and an elastomeric ring located in the retaining ring groove.
 5. The assembly according to claim 1, wherein the retaining means comprises: a circumferentially extending groove segment on an outer side of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; a resilient ring having an inner diameter side in contact with the retaining ring groove; and the resilient ring has an outer diameter side spaced radially inward from any portion of the collar.
 6. The assembly according to claim 1, wherein each of the ring segments has two ends, and the retaining means comprises: a roll pin protruding from at least one of the ends of one of the ring segments that is received within a hole in at least one of the ends of the other of the ring segments.
 7. The assembly according to claim 1 wherein, each of the ring segments has first and second ends, and the retaining means comprises: a hinge connecting the first end of one of the ring segments to the first end of another of the ring segments; and a roll pin protruding from one of the second ends that is received within a hole in the other of the second ends.
 8. The assembly according to claim 1, wherein each of the ring segments has two ends, and the retaining means comprises: a pawl protruding from at least one of ends of one of the ring segments into engagement with a lip on at least one of the ends of another of the ring segments.
 9. The assembly according to claim 1, wherein each of the ring segments has two ends, and wherein the retaining means comprises: a detent on an inner diameter portion of each of the ring segments adjacent one of the ends of the ring segments; and a mating detent recess on the neck that receives the detents.
 10. The assembly according to claim 1, wherein each of the ring segments has two ends, and the ends of one of the ring segments are closely spaced to the ends of another of the ring segments when the ring segments are installed around the neck.
 11. An electrical submersible pump assembly, comprising: a plurality of modules including a pump, a motor, and a seal section for reducing a pressure differential between lubricant in the motor and hydrostatic pressure of well fluid; a drive shaft assembly having an axis and extending from the motor through each of the modules; a threaded connection between at least two of the modules, comprising: a first adapter having external threads; a second adapter having a neck with an external load shoulder; a collar rotatably carried and axially movable on the neck, the collar having internal threads that engage the external threads of the first adapter, the collar having an internal load shoulder axially spaced from and facing toward the external load shoulder; a shoulder ring encircling the neck and comprising two separate ring segments, each of the ring segments having ends that are closely spaced to the ends of the other of the ring segments, the shoulder ring having a first surface in abutment with the external load shoulder and a second surface in abutment with the internal load shoulder to transfer an axial load between the first and second adapters; and a resilient ring that fits around an outer diameter of the shoulder ring for retaining the ring segments on the neck prior to the collar being in threaded engagement with the threads of the first adapter.
 12. The assembly according to claim 11, further comprising: a circumferentially extending groove segment on an outer side and extending between the ends of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; and wherein the resilient ring fits in the retaining ring groove.
 13. The assembly according to claim 11, further comprising: a circumferentially extending groove segment on an outer side of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; and wherein the resilient ring is elastomeric and fits in the retaining ring groove.
 14. The assembly according to claim 11, further comprising: a circumferentially extending groove segment on an outer side and extending between the ends of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; wherein the resilient ring has an inner diameter side in contact with the retaining ring groove; and the resilient ring has an outer diameter side spaced radially inward from any portion of the collar.
 15. The assembly according to claim 11, further comprising: a circumferentially extending groove segment on an outer side and extending between the ends of each of the ring segments, defining an annular retaining ring groove when the ring segments are installed around the neck; wherein the resilient ring is elastomeric and has an inner diameter side in contact with the retaining ring groove; and the resilient ring has an outer diameter side that does not seal to any portion of the collar.
 16. A method for assembling an electrical submersible pump assembly having a plurality of modules including a pump, a motor, a drive shaft assembly having an axis and extending from the motor through each of the modules, a threaded connection between at least two of the modules, the threaded connection comprising a first adaptor having threads, a second adapter having a neck with an external load shoulder, and a collar rotatably carried and axially movable on the neck, the collar having an internal load shoulder axially spaced from and facing in a direction opposite to the external load shoulder, the method comprising: positioning a shoulder ring having two separate ring segments around the neck, and with a retainer, retaining the shoulder ring on the neck; then moving the collar axially past the retainer and threadingly engaging the collar with the threads of the first adapter, placing a first surface of the shoulder ring in abutment with the external load shoulder and a second surface of the shoulder ring in abutment with the internal load shoulder and transferring an axial load between the first and second adapters.
 17. The method according to claim 16, wherein retaining the shoulder ring on the neck comprising installing a resilient ring around an outer diameter defined by the ring segments.
 18. The method according to claim 16, wherein: retaining the shoulder ring on the neck comprising providing an annular groove on an outer diameter defined by the ring segments; and fitting a resilient ring in the annular groove.
 19. The method according to claim 16, wherein: retaining the shoulder ring on the neck comprising providing an annular groove in an outer diameter defined by the ring segments; and fitting an elastomeric ring in the annular groove.
 20. The method according to claim 16, wherein: retaining the shoulder ring on the neck comprising providing an annular groove in an outer diameter defined by the ring segments; fitting an elastomeric ring in the annular groove; and positioning an outer diameter of the elastomeric ring radially inward from and out of contact with any portion of the collar. 